¡Colores!; 610; Trinity: Getting the Job Done; Bob Henderson 1

Well, the early work at Oak Ridge was of course to get the plant running one way or the other together running, but then as we got into that, the problem was what can we do to improve the quality of the product? In other words, the purity, if you will, of the Radium 235 that we were getting out of the system, and you could do it by tuning what we already had in place, or by going back to the drawing board and designing, but in the oil refinery business you call topping plants or ways of improving the quality of a product already produced, rerunning it in order to improve its quality. And so that was why I left Oak Ridge to go back to Berkeley to get on with the second generation, the means of improving the quality of the product coming out of Oak Ridge. And it was in the middle of that when Oppenheimer and Kiszykowski got out to Berkeley to talk

to me. They obviously had been talking to Lawrence some length prior to that time, and Lawrence had indicated that he had the guy that could do what they were looking for. So I was working on this improvement to the Oak Ridge product when they came in, and that, of course, got interrupted in the big hurry as I mentioned the other day. Okay. Remember that what we said? I'm sorry, we got a little problem. Lawrence's introduction to what these fellows wanted to talk about was simply these guys want to talk with you about doing something different, and I don't want to say anything more. Let them do their own talking, but it's a different deal as far as your concern. And so I walked in on them not knowing really anything about what they wanted to talk

about. So it was quite a surprise to me. And the way Oppenheimer led into it was kind of interesting. It's a lot of you repeating any of that. Yeah, let's see. That's right. I want to do the whole thing over. Oppenheimer did not reveal anything to me, neither did Kiszykowski in their conversation is to really what they wanted me to do. He just outlined the fact that there was going to be a new world for me, a change of activity completely. And from what they knew of me in my background, they thought that I was in natural to get on with a job. And that's when Oppenheimer asked me what I knew about the National Geographic's advertisements of boarding schools for kids. And when he said that they were at the Los Alamos Ranch School for boys, back in Santa Faye in the mountains, and it was an isolated place.

And that was his main claim that there was nothing much around there. So I knew that there had to be some place in the United States where somebody was building a weapon because I knew about the people that were building the material, making the material to be used in a weapon, but I had no idea where they were actually designing a weapon. So this was new to me, and things began to come into focus at that point. Okay, let me, let me run, I'm sorry. I mentioned Oppenheimer and Kiszykowski at the time that I was up to my ears at the moment on a job for Oak Ridge, but at about a week's work to do, and then I'd be real happy to come down and see them. And that's when Oppenheimer said, well, I have a ticket here for you and your name on a plane leaving in three hours from San Francisco.

And so I sort of got the message at that point that this was it. I went home, packed a small bag, figured I'd be going maybe three, four days, something like that. And then we went back, talked some more and went over to San Francisco to catch the airplane. The trip from San Francisco to Santa Fe was different than it is nowadays. In those days there were nothing but DC-3s, and they stopped everywhere. They stopped at Fresno, Los Angeles, Phoenix. Across the river and then into Albuquerque, where we were picked up by an army vehicle driven by a black driver, then on to Los Alamos, which in those days was quite a little

experience in itself. The roads were not highways, they were just neighborhood roads that wandered their way up the mountainside. I was put up in Fuller Lodge, which was the main hostelry then for visiting Elks that had to come to the laboratory, many other facilities, and had a little corner room there, and that turned out to be my home for the next approximately three months before I could get home to collect my wife and baby. So you were really shanked, right? That's the correct word, really shanked. And they provided me with all the tools that I needed, I didn't have to worry about the lack of books, the slide rules, or anything like that, everything that I needed. And then I was introduced to people that would be working with me, and we went from there. Go ahead, I'm sorry.

What's going to say, let's pick it up with Kishtia Kowsky, what's responsible for the implosion weapon, the high explosive system, the weapon we dropped on like a saki, as contrasted to the bomb that we dropped on Hiroshima, the gun type gadget, which was nothing more than a gun. They project on the target, and the two of them became super critical and made an explosion, but very, very inefficient. Kishtis was much more sophisticated, and nobody knew that we would even work, and that was the big question mark. We had to test it. We knew we had to test it. We did not have to test the one that we were going to drop on Hiroshima in a full squeal version.

So I had two jobs. Working for Kishtia I was to do the engineering necessary to produce the high explosive charges that he would use in the implosion gadget. And secondly, to work with Kenneth Bainbridge, who had been brought in from Harvard, to act as the director of the test facility at what we came to call Trinity, down near Scoral, part of the Alamagordo bombing range, two jobs, and the more confining one was the one working on the explosive charges for the weapon itself. Let's talk about that, because that's some new area for us. The explosive charges, I mean, you told me a lot of interesting things about the refinement of the crystals, being in the hell out of those blocks to get them in the place.

I mean, there was lots of fun things you went through, let's talk about some of that. The quality of the quality that we required to guarantee is uniform detonation velocity. We're just not available. We had to take a commercial product from the Holston Ordinance Works and melted and then purified, and by selective chilling of it going from the liquid to the solid form, control its crystalline size, because the detonation velocity was sensitive to the crystalline structure of the explosive itself. We needed two different kinds of explosives. We needed a fast detonating one, 7,800 meters per second, and we needed a slow detonating one. We used barato, that was a barium nitrate compound, 5,200 meters per second. That's Yikovsky, especially, was the explosive's chemistry.

And so he was right at home in coming up with ways of purifying the explosive. And the casting of it, controlling its transition from a liquid form to a solid form, was a more of a mechanical problem, where we had to use cooling circuits, tubing to cool the moles in a very pre-arranged way to get the crystals away we wanted. And then we'd saw them apart and checked the crystalline growths and go from there. I learned a lot about explosives that I didn't know you could do, that you can machine them in machine tools, you can cut them in layers, you can use milling machines on them, you can take a saw and cut them, but you gotta be careful that you're using the non-sparking tools, the brilliant copper and things like that. You don't want to use steel cutting tools when you're sawing explosive. Always read about sparks.

But they had been playing with these kinds of things for quite a long while and had a good way of doing it, drilling holes in them, you could take an ordinary drill and drill through explosive well, you could, but it's probably not a very healthy idea. So they had special drills for going through explosive. It's interesting in all the years that they were working with cast explosives at Los Alamos, there were very few serious accidents. The work was done by remote control and explosion chambers, that is the machine tool that was doing the cutting, it was isolated from the operator by big explosive walls, so that if there was a blow, it would just blow out across the countryside and wouldn't hurt the operator who was shielded by a concrete wall, but looking through bulletproof glass. So that was pretty routine after we got into the business, but- Tell us what you were doing, to sum up, you were just physically cutting, slicing,

dicing to make these lines right. Making various shapes for experimental purposes, making various shapes of explosive, which had been cast in chunk form and then by machine tools, by conventional machine tools, except they were non-sparking, we would machine them into whatever configuration we wanted for these test purposes. These were not for a specific weapon, they were test devices, in order to measure certain physical properties of the explosive itself, so there was a lot of that sort of thing going on all the time to feed the experimentalists. The casting of the blocks for the finished weapon was a different matter. Here we were going in a very specific direction and wanted to get a very uniform product, one after another, and many of them, and then test enough of them to know that we did in fact

have a uniform product and to go from there. So in addition to getting the quality of the explosive, what we wanted, the way we would assemble them, was something of a problem, because here you had 64 separate blocks of explosive, two layers of 32 blocks each, and they all had to be compressed into a spherical configuration, and there's no way you could calculate this. It was cut and tried, just by practicing with the explosive, and using shimming material, we could finally work out a scheme whereby we could compress the blocks to the degree that we wanted, and we had instrumentation available, which Roy Carlson had provided from Berkeley, to measure the pressure on these blocks, and make sure that there were not excessive

pressures in some locations and insufficient pressure at other locations. This was all done by instrumentation, so we knew where it wasn't guesswork after we got into it. What were you trying to do by the arrangements at the height process? We wanted to get a ball, a spherical ball, about 53 inches of diameter, in which would be enclosed the nuclear material to be compressed to give us the detonation, and so the whole trick here was to provide a mechanical means of compressing all these 64 blocks of explosive into a uniform sphere, which in turn, then, could withstand the rigors of flight. These would be carried in the bomb bay of an airplane where the temperatures were way

below zero, and starting out at room temperature, the question was, what's going to happen? As everything shrinks when they get chilled, is the ball going to come loose inside its case, if so, how badly so? A lot of experiments had to be run on these compressions to make sure that under the kinds of temperatures, and for the length of time, it would be airborne at temperatures way below zero, that nothing of a shrinkage nature would take place that would cause worries or concerns about it. They were also worried about enemy attack, anti-aircraft attack, either from fighter planes or from flak, anti-aircraft guns. How could you protect this bomb in the bomb bay in any way so that you would be reasonably sure that it wasn't going to get blown up by enemy action? We did a lot of experiments on that.

I guess one of the most interesting ones was we took a complete assembly of 5,300 pounds of high explosive, and set it up on the ground across one of the canyons up there in the Solomon's Mountains, and then sat down in a dugout, and we had a 20 millimeter cannon down there, shooting high explosive shells across the canyon at this ball of explosive and the whole deal was, can we blow it up or can't we, or can we set it on fire? It's interesting enough that even with high explosive shells, 20 millimeter in diameter, we never ever were able to detonate that ball of explosive. It survived it. So that made us feel pretty good about the whole assembly being insensitive to enemy action. Can you sum up to me the challenge of figuring this all out?

It was all cut and tried. We had military types in our various groups who had experience in various areas. This business of detonating explosive was shell fire. We had falls around that had played with that before. They had an idea of what you could get away with and what you couldn't. So we weren't completely in the dark, and they were guiding us in the kinds of experiments we were running to see that the explosive would be safe. Yeah, but this was just pure experimentation. Pure experimentation. All this stuff was, we didn't have time to get sophisticated about anything. In fact, all the way through the design of the weapons, we couldn't start from scratch and design a component specifically for our application. It was almost always what is on the market?

What is available that we can modify or gang up with something else to do our job without getting into a lot of development work on some new, untried component, use what's available. And that philosophy prevailed through the design of the whole weapon. That's why we call the thing a gadget. It was certainly not a well-engineered affair. We got around to doing that after the war, but the ones we used in Japan were cobbled up from existing hardware, and now hardware in itself put together in series parallel arrangements to make up for the deficiencies that it might have in some particular area. Make do with what you can get your hands on, and then play with it enough to know that from all of your experiments that, yes, you can rely on it, and it'll do the job we want.

It was particularly true of the fusing of the bombs, which were radar proximity fuses. We took a tail-warning radar from the air core. This was a device that was in the tail of airplanes, and it let the pilot know if somebody was shooting at him. It listened for somebody that was spraying them with radiation from a radar set, and so he knew he was in trouble with somebody who was on his tail. We would take those standard items that were available, and then by linking them up in series parallel arrangements to make up for their individual deficiencies, we could come up with a system, a fusing system, which would do the job reliably. And instead of like on a radio where you have a dial to tune things, we wanted the people to set these radars to fire at different altitudes, we didn't have any dials like that.

We had to just point wires to the right length, so you would get in there and trim things inside the radar, such that it would fuse itself, it would close the circuits when we wanted it to. No fancy stuff like dials on radios, that was not a lot, I didn't have that. So it was cut and try all the way through, cut and try, and make sure that you had enough experimentation behind you to assure that you could do the job that you wanted to do.